The Role And Mechanisms Of Caveolae And Caveolin-1 In The Progression Of Autosomal Dominant Polycystic Kidney Disease

Objective:Autosomal dominant polycystic kidney disease(ADPKD)is characterized by uncontrolled cyst growth,lacking effective treatments.Our research aimed to elucidate the role of caveolae and caveolin-1(CAV1)in the progression of ADPKD,and thus to shed light on novel treatments in ADPKD.Methods:1、 Analyze the correlation between CAV1 expression and cyst volume via bioinformatics,and detect the expression of CAV1 and caveolae in multi ADPKD models including in vivo and in vitro models by Western blot,real time PCR(q PCR),immunohistological analysis and electron microscope.2、 Administrate HP-β-CD,an inhibitor of caveolae and CAV1,on early and late onset ADPKD mouse models and then analyze the kidney weight to body weight ratio and renal function of mice to verify the effect of HP-β-CD on ADPKD.Utilize immunohistological staining and electron microscope to detect the inhibition effect of HP-β-CD on caveolae and CAV1.3、 Extract the endosomes of RCTEC and WT9-12 cells,and use TMT quantitative proteomics technology to find differentially expressed proteins in the endosomes.The levels of screened endosomal protein were verified by Western blot and q PCR.Moreover,the abundant of S100A7 in the cell supernatant of RCTEC and WT9-12 and cyst fluid of patients with ADPKD was tested by ELISA,and its function was analyzed by adding recombinant protein and overexpressed protein coding gene in cells.4、 Use CAV1 specific si RNA and HP-β-CD to inhibit caveolae and CAV1,and then,to discover the role of CAV1 in mediating cell proliferation induced by S100A7 by Western blot and immunofluorescence.Results:1、 The expression of CAV1 is positively closely correlated to the size of renal cysts.CAV1 and caveolae are highly expressed in the cyst lining epithelial cells in ADPKD.2、 Using HP-β-CD to treat early-onset and late-onset ADPKD mice can effectively inhibit the growth of cysts,and decrease the kidney weight to weight ratio,Ki67 and PCNA positive cells in immunohistochemistry of mice.In early-onset ADPKD mice,HP-β-CD can improve the renal function of mice.3、 A total of 615 differential proteins were identified in the endosomes of RCTEC and WT9-12 cells,of which 361 proteins were significantly correlated to CAV1.The most relevant up-regulated protein is S100A7.The levels of S100A7 in the supernatant of WT9-12 cells and in the cyst fluid of ADPKD patients were increased.S100A7 induces the activation of ERK and Akt,and promotes cell proliferation.4、 S100A7 induces the phosphorylation of CAV1,and p-CAV1 mediates the activation of ERK and Akt induced by S100A7.Both CAV1 specific si RNA and HP-β-CD can inhibit the activation of ERK and Akt pathways induced by S100A7.Conclusions:In the ADPKD microenvironment,the synthesis and secretion of S100A7 by cyst lining epithelial cells increases.S100A7,which is secreted to the extracellular component,enters the cell through caveolae and CAV1,further promoting cell proliferation.Clearing caveolae by HP-β-CD or inhibiting the expression of CAV1 can break this effect,thereby reducing the phenotype and slowing the progression of ADPKD.